If I search for part of a word results vary. For example, if I want to use as global search parameter "meeting", but write it incompletely, let's say "meeti", no results are returned. The same thing happens if I use "meetin". If I use "meet", or "meeting" correct results are displayed. This is critical when you are looking for part of a complex word or surname and you don't know the exact spelling. Quick search does work as intended, but only looks in one folder at a time.

(not dependent on 64bit, so no keyword) google search results are similar https://www.google.com/search?q=meeti&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:unofficial&client=firefox-nightly&channel=sb you are using an example where the search term used is not a stem of a word, nor a proper word itself. see bug 523183 comment 11