I've not convinced "meatatarian" or any other derivation is a real English word. It certainly is not in the Oxford dictionary. It sounds like a word that has been made up to counter the word "vegetarian", but if such a word existed then it would mean someone who exclusively ate meat (ie a carnivore), just as "vegetarians" exclusively eat vegetation.
If you mean somebody who eats anything, the word you are looking for is "omnivore", although this is really a classification that describes all humans as a species - being a vegetarian is a matter of choice. Informally, most people clarify that they are not vegetarian by simply saying they are a "meat eater".