Having some knowledge of fire code stuff I can tell you that sprinkler codes, or any expensive code change, will not be required of the night club unless they do a remodel to their occupancy. I believe the term is Grandfathering.
If it is really that big of a nuisance then the other neighbors may be po'd as well? Why don't you guys get together and go talk to the nightclub owner about their clientel. This DOES work but it will require a lot of effort on your part.
Also, you can call 911 and complain like everyone else. Eventually the cops will take notice and they will lean on the establishment owner's.
That's how it works over here FWIW.
joe.