Bumdog, it is my understanding that you have to have actual first hand knowledge of the person commiting a felony to be able to place him/her under citizen's arrest. Of course, you didn't state what state you're in either. And that could very well be different in each state. But calling your boss out for a fight? Sounds foolish to me. But I must confess that if I were in your shoes, with what you have said so far, I would have done the same thing.
Just because he calls you a "nigger" does not mean you can arrest him or have him arrested. But, if he is your employer, I'd say contact the EEOC and get a lawyer. Racial discrimination is illegal in the USA. He can do what he wants in his home contry, but this is the west, not the east.
I ain't a lawyer. I ain't a copper. I'm a true blue American that believes in Freedom for all. Provided they ain't criminals.