How to perform advanced searches on db

[eluser]Unknown[/eluser]
Hello everybody!

I'm currently developing an application using CI but I'm stuck writing a decent internal searche engine.
My main problem is that I can't use mix urls with CI, and so I have no idea of what would be the right path to follow.
My goal would be to perform fulltext searches on the db via a simple form with one input field, or more complex searches via a form with multiple params.

Can someone please help me?

I searched the entire forum but it seems anyone talks about this problem.