How can I search for another user using phone number ?

I am trying to expand the scope of user search by providing search on fields like phone number or city or any of the information that I might store in a vCard. How do I search and come up with a list of users from Smack client based on an expanded search criteria such as Phone number or City ? The default setting of searching by just username or Name is very constrainted in its use for me.

Thanks for your help.

Krishnan