Do I call them clubbers or are there better words to describe them?
Word choice depends on what aspect of behavior you emphasize — drinking, dancing, talking loudly.
A carouser is one who "engages in a noisy or drunken social gathering".
Some far-less-specific words often used in the context of bar patrons are regulars, denizens ("One who frequents a place. [E.g.] The denizens of that pub are of the roughest sort."), and habitués ("One who frequents a place; a denizen or regular [E.g.] A month ago the new smoking ban turned thousands of bar-room habitues into reluctant exiles...")
It is a slang. The activity of frequently visiting bars and clubs is clubbing.