Have one search text box without selecting fields

Hello everyone,

I love using site user list as it's the only tool that does what I wanted :-)
Except...I would like to have one text box when users want to search.
One without selecting wich field they want to search.

So when our users press search, they only thing they would get is a textbox.
Even beter would be, having a simple text box above the user list saying search.

Hope someone can help me out a bit!

Thx