Regular Expression to find XML tag

I have an XML in the following format

<Employee>
<ID>..</ID>
<E-mail>..</E-mail>
 ...
<custom_1>..</custom_1>
<custom_2>..</custom_2>
 <custom_3>..</custom_3>
 </Employee>

My requirement is to find all the tags in the XML which starts with "custom_*". I'm using Groovy an hence doing something like this (using XMLParse in Groovy)

Could anyone please guide me here.

Thanks, Vipin