ya surely "genki desu-ka?" means "how r u" in japanese. but in daily life, japanese never say so cause its too literaly like "how do u do" in English. so we dont have basic way to say "how r u" in practically. its case-by-case. i suggest u to say "ohayou(gozaimasu) / konnichiwa / konbanwa" = "good mornin / hello / good evenin" these r easy and acceptable^^

You would say こんにちわ！　　　　　　（Konnichi wa!）　 greeting used during the day 元気ですか？　　　　　　（genki desuka?） how are you? はい、元気です。　　　　（hai genki desu） I'm fine. Good luck!!!