I don't know if anyone still cares as this question was posted long ago but here is the answer:
If you want to use the meta fields in search you have to make them indexed fields.
To do this you need to make a change on the indexer.
In fields.conf add the following:
After that you should be able to use 'environmnt=' in your search. And you should also see those two fields show up in the fields list.