Searching all fields instead of choosing one

I do have a search related question, and was hoping someone could answer.

In my search page, I have a few fields to search. Let's take state for example.

When users sign up, they choose their state. Is there a way that if they want to search for certain users by ANY state, and not select a state in the drop down box, that the database will spit out everyone from any state that matches the other criteria?

I hope that makes sense. It's hard to explain, but just want them to choose other options, let's say search for a certain age from any state.

Thank you so much!

It is an issue that is difficult to explain, and I believe your problem might be related to the inability of D7 to select "null" for a field.  It has been partly, but not entirely, solved at this link: http://www.boonex.com/unity/forums/topic/HOWTO-create-join-form-field-with-Not-Specified-.htm