I need to search AU users by more than just username - actually by location, bio or website. Is this possible? In the users tab search only works by username only.
Moderators can search by a few extra terms. If you desperately need to find a person —and have a good reason— bug one of us and we'll try to help you.
Additionally the public data is accessible through data.stackexchange.com. You can compose a SQL query to search from a number of fields, including location, bio and website. Here's a simple search on the bio field which finds my user:
SELECT * from Users where AboutMe like '%thepcspy%'
Note that the data.SE engine works on a slightly old database. I don't know what the delay is these days but it isn't current. It should be good enough for most purposes though.
You can also download the SE Data Dumps and do things manually... Though they are 25GB compressed.