[drupal-support] Search example

Hi, I have implemented the search hook in a module I am writing, but I was wondering if someone has an example of the search implementation where I can search for more than one field. Currently I can "Enter your keywords" and that's it. I want to choose from a bunch of fields and adapt the query to match the selection. I can manage that if I know how to get the extra fields in the search form. I can't see anything in drupaldocs that gives me a hint as to how I can do this. Thanks in advance, Kobus