"Wie geht's?" or "Und wie geht's dir so?" implies "How have you been?". :-) If you meet someone you haven't met for a long time, he would start telling you about everything important. "Was machst du so?" is even asking explicitly for that kind of information. "Hallo, habe schon lange nichts mehr von dir gehört. Was machst du so?" is a perfectly fine first line in such a dialog that could actually happen. And don't be surprised if a German person starts telling you all about his or her current and past problems after you ask "Wie geht's?" or even "How are you?" if you're speaking English. It's not like the expected answer is only "I'm fine, and how are you?" :-)

Wie gehts?

We don't really ask "how have you been". As it was pointed out, "Wie geht's?" kind of already carries that meaning in it. However, if you wanna put some emphasis on the "how have you been" aspect, you can say "Was gibt's Neues?", which would also mean something along the lines of "What have you been up to?"