"I can't wait to ~" = "나는 어서 빨리 ~하고 싶어." "I can't wait to meet you " = "난 어서 널 만나기를 바라고 있어."(written) = "나는 어서 빨리 너를 만나고 싶어."(Written) = "어서 만났으면 좋겠다~~" (Spoken) "I can't wait to hear your voice tonight" = "나는 (어서 빨리) 오늘 밤 너의 목소리를 듣고 싶어." (written, spoken)

Don't translate it literally. If you'd say, "기다릴 수 없어요", it would sound like a decline, like "I don't want to wait for you." That's the opposite of what you want to express. So how can you say it? 다시 만나기를 기대해요. - I'm looking forward to meet again! 연락을 기대해요. - I'm waiting for your phone call. 보고 싶어요. - I miss you. (very common among young couples) 그리워요. - I miss you. (very emotional.)