I agree with the posters who suggest asking "what's the best way to get a taxi from here?". You can ask a client or a doorman or anyone else you meet. It's a civil question that, IME, is a common occurrence at the end of a meeting. But always phrased as a question, not as claiming a right.

The transaction then usually proceeds with:

Client/doorman: ah, I know a good company - reliable and fast - I'll give them a call. Where are you heading?

You: thank you, that's very kind. I'm going to the airport, please

Client/doorman: That's a pleasure; it'll be here in ten minutes. Do take a seat over there.

Both parties feel warm and happy at the thought of a good deed done for the day.