A person with two languages is bilingual. A person with three or more is multilingual. Looking for a word that describes the exact number of languages would seem disingenuous.
You would be called a quadrilingual.
People who speak several different languages are called polyglots.
four
Christine Lagarde is known to speak fluently in English and French. She may have some proficiency in other languages, but these two are the main ones she is known for.
Anton Yelchin was fluent in English and Russian.
Four
You are likely a polyglot, someone who is fluent in multiple languages. This demonstrates a high level of language proficiency and a diverse cultural understanding.
multilinguist, polyglot; use dictionary.com for more reference
Trilingualism.
Guus Hiddink can speak Dutch, English, German, and Russian.
Poly-lingual ... poly meaning 'many' & lingual meaning 'tongue'They speak many tongues.
Trilingual