How I search contacts by field other than name e.g. category iPhone

I recently switched from Blackberry to iPhone 4, and I use my iPhone 4 primarily for business. I have a PC and use Outlook as my contacts application.
I regularly populate my Outlook contact records with various notes, and I regularly categorize my contacts. With Blackberry I could (and regularly did) search my contacts by fields other than by contact name (e.g. words which I had entered into fields such as Notes, City, State, Company, or Category, and this was very useful. For example, if I created a category called Accountants and categorized 3 contacts in that category, I could search my contacts for Accountants on my Blackberry and it would show a list of the 3 contacts I have who are Accountants. Or if I wanted a list of all contacts who reside in Chicago so that I can put together a slate of meetings during a visit to Chicago, I could search my contacts for Chicago and the search would result in a list of all my contacts with Chicago in their record (either in location, category, or notes fields).
With iPhone 4, so far Ive only figured out how to search the name fields of my contact records, but hopefully it is possible to search other fields or the entire contact record. How do I do that?
Thanks.
Dell PC Windows XP