How to perform search with 3 input fields in a form?

Hi! I found the tutorial and script very very useful so far! What I am after is how would I go about changing this script so I can have 3 input fields and one search button? Let say I am looking for a gardener (field1) in London (field2) or/and a business name called green hands (field 3). Very very similar to yellow pages (business director). This is a link to the page I am working on> http://www.artishock.net/search/01.htm ; If any one can help I will be the most grateful.
Roland