Meeting invitation

How do you say ''if you can spare some time, afterwards, can we meet for a little bit?''

Which is better?
（時間を割いてくれたら）
「後で少しでも会ってくれませんか？」
「後で少し会っても良いのでしょうか？」
「後で少し会っても高｢ませんか？」

The other person is of a higher status than me, so I don't want to be rude, but I don't want to be too formal, either, because we're not exactly in a business relationship.

He's something between a boss & a pupil so I'm not really sure how to interact with him.

Out of the three, the first one is ok. (The second and the third ones are asking "is it OK I meet?" and a bit... clumsy.) But you are meeting with that person as you say those words, I would rephrase it to ask if "could you give me some time" rather than "can we meet."

If you are asking someone of a higher status than you, I would suggest:

お時間がありましたら、(If you have time) or もしできたら(if possible)
あとで少しお時間をいただけませんか (afterward, could you give me some time?)
or with an equal:
時間があったら、
あとで少しお時間をもらえませんか。

"He's something between a boss & a pupil".
It means you are teaching something, i.e. English to him or teaching a class that he is attending & learning (English)?
Are you a male or female?
For a neutral relationship knowing he is your boss but at the same time he is your seito & you are his sensei in a friendly term, この後、少し時間ありますか？
If you are a female, この後、少しお時間ありますか？

Thank you AK & ay!

AK--
I'm thinking of sending a text message or e-mail with that phrase, so would "お時間がありましたら、少しでも会ってくれませんか？" be alright?

ay--
I was teaching him English & helping him to translate some things, but it was casual (as in he didn't pay me, but his company would pay for dinner/lunch/snacks).

By the way, it's been a few years since we've met in person. Is "ご無沙汰しております" too formal?
I don't think he likes being formal since whenever we met, he always called me -chan & didn't use keigo. I used keigo & -san since he's older. Also, when I sent him an business-like message saying "お世話になりました (etc...)" he didn't reply, but later on when I sent him a message saying "good luck" & "時差ぼけですか(笑）(etc...)" he promptly replied.