I am also a Google Calendar power user and might have you beat in terms of the number of calendar entries I have (though I don't know of any easy way to find that statistic out without exporting the data and running it through some filters). Well, this probably isn't a test, however, so let me just say that I know where you're coming from!

There are a couple of ways that you can restrict a search to a specific field in your calendar entries, and the easiest of which can be found if you click on "Show Search Options" right on the Gcal home page:

A whole world of search options appears once you do that:

Be careful, though, if you hav emore than one calendar included: by default it searches all calendars which might not be what you want. I have a half-dozen odd calendars, for example:

For me it's important to choose "Dave Taylor" so that Gcal doesn't give me matches from other calendars.

As an example, a quick search for "Jill" in the Location field yields the following on my own calendar:

Notice that the search has become "where:jill" with this search. That tells you that, yes, if you want to just type in a search into the search box, you can preface the word or name you seek with "where:". In your case, "where:mike".

Other predicates you can use include "who:" and, if you want to search for Mike but not Mike Smith, for example, negative matches "-smith". So, to put it all together, lunch where:jill who:richard would find all the Google calendar entries that were lunch at Jill's with Richard.

Hope that helps you dig out the event or events you seek.