Not sure what problem you're having with this, you look to be on the right
track.

I think that you may be having trouble getting the desired results when you
leave one of the fields blank?

If so, change your statement to:

=[Forms]![formname]![controlname] & Like "*"

or similar.

Also, if you are using several criteria for several fields, make sure you
watch the "and" and "or" conditions.  Placing all the criteria on the same
row at the bottom of the criteria grid means that each item must match.
Since you are including "blank for all" conditions, this is most likely what
you want to do.

Hope that helps,