I'm not certain that I'm phrasing my question correctly, but I couldn't think of a better way to word it. What I'm asking is for a word that truly defines to mean a person who solicits prostitutes. I've heard of the slang word "john", but that's not a satisfying answer to me. "Whore" and "prostitute" unambiguously mean a person, connotatively female, who trades sexual favors for money, with whore being more derogatory and prostitute more meaning the actual profession. "John" doesn't quite do this, it's meaning isn't so clearly explicit in the word.
So, is there a word that does this? As a secondary question, if there is not a word in English, is there one in another language?
An example of how this word would be used: We can't keep the blanks away from the new escort service that opened downtown.