Results by Label Report

To answer your question, I don't think you can do what you're looking for in the Labels report - it would need to have a post-generation function to click labels on/off like it does for the execution statuses.  If it was sufficient for you to see a list of test cases that fit your criteria, that is possible using the logic I described above: you would see only test cases that have a label IN(x, y, z), but this is a very different report to what you were originally looking for.

If you could describe your use case I might be able to help suggest an alternative way to achieve the same result.  Alternatively, you could export the dataset from your report and work with that in Excel - I don't know of any other option.