How to create SOAP request to match XML without CURL through PHP

I have to create the following XML request using SOAP:

<SimpleRequest>
    <MessageHeader SegmentId="MSGHDR">
        <MessageId>CCREQ1</MessageId>
        <SessionId>12345</SessionId>
        <ReqCode>PL</ReqCode>
        <UserName>USA123</UserName> 
        <AgencyId>5588</AgencyId>
        <UICode>5</UICode>
    </MessageHeader>
    <RoomAvailabilityRequest SegmentId="REQ1">
        <RoomId>A14</RoomId>
        <Date>05112016</Date>
        <DurationDays></DurationDays>
        <Embark Code="SFO"/>
        <Debark Code="EWR"/>
        <Transport Code="CA"/>
        <City Code="EWR"/>
        <Currency Code="USD"/>
    </RoomAvailabilityRequest>
</SimpleRequest>

I have tried the following but it keeps failing:

<?php

$url = "http://ift.tt/1FrStMj";

$client = new SoapClient(null, array(
    'location' => $url,
    'uri' => $url,
    "trace" => 1,
    "exceptions" => 0));



$xml = '<RoomAvailabilityRequest SegmentId="REQ1">
               <RoomId>A14</RoomId>
               <Date>05112016</Date>
               <DurationDays></DurationDays>
               <Embark Code="SFO"/>
               <Debark Code="EWR"/>
               <Transport Code="CA"/>
               <City Code="EWR"/>
               <Currency Code="USD"/>
           </RoomAvailabilityRequest>';

$params = new SoapVar($xml, XSD_ANYXML);


$arr = array(
    $params
);

$xml_header_string = '<MessageHeader SegmentId="MSGHDR">
                         <MessageId>CCREQ1</MessageId>
                         <SessionId>12345</SessionId>
                         <ReqCode>PL</ReqCode>
                         <UserName>USA123</UserName> 
                         <AgencyId>5588</AgencyId>
                         <UICode>5</UICode>
                      </MessageHeader>';

$xml_header = new SoapVar($xml_header_string, XSD_ANYXML);

$header = new SoapHeader('http://ift.tt/1C5pQFZ',
                               "MessageHeader",
                               $xml_header);


$value = $client->__soapCall("SimpleRequest", $arr, null, $header);

print "<pre>\n";

print "<br />\n Request : " . htmlspecialchars($client->__getLastRequest());

print "<br />\n Response: " . htmlspecialchars($client->__getLastResponse());

print "</pre>";

This is what the PHP produces as a request:

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://ift.tt/sVJIaE" xmlns:ns1="http://ift.tt/1FrStMj" xmlns:ns2="http://ift.tt/1C5pQFZ" xmlns:xsd="http://ift.tt/tphNwY" xmlns:SOAP-ENC="http://ift.tt/wEYywg" SOAP-ENV:encodingStyle="http://ift.tt/wEYywg">
    <SOAP-ENV:Header>
        <MessageHeader SegmentId="MSGHDR">
            <MessageId>CCREQ1</MessageId>
            <SessionId>12345</SessionId>
            <ReqCode>PL</ReqCode>
            <UserName>USA123</UserName> 
            <AgencyId>5588</AgencyId>
            <UICode>5</UICode>
        </MessageHeader>
    </SOAP-ENV:Header>
    <SOAP-ENV:Body>
        <ns1:SimpleRequest>
            <RoomAvailabilityRequest SegmentId="REQ1">
                <RoomId>A14</RoomId>
                <Date>05112016</Date>
                <DurationDays></DurationDays>
                <Embark Code="SFO"/>
                <Debark Code="EWR"/>
                <Transport Code="CA"/>
                <City Code="EWR"/>
                <Currency Code="USD"/>
            </RoomAvailabilityRequest>
        </ns1:SimpleRequest>
    </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

Please help me create this XML needed. Let me know if any more information is required. Thank you in advance.