It seems you don’t have a strong connection with the partner besides the meeting you had some months ago; I believe thus that, if you write him, he will forward your application directly to HR. On the other hand, a direct application via HR would lead to no referral at all.
A better option could be to obtain a referral with someone else that you could reach in your network; to do so I would follow the steps below:
1. Identify the ideal connections to contact. LinkedIn could be a good starting point for that (another option is to use your university alumni database, if available). Former alumni of your university normally represent the strongest connections.
2. Write a customized cold email. I would recommend using emails rather than LinkedIn messages, as writing via LinkedIn you would immediately be perceived as a stranger (there are ways to easily find the email of everyone nowadays in few minutes). The email should follow some specific rules for the subject and the content, in order to maximize conversion.
3. Have a call with the consultant, and indirectly ask for a referral. The call should be structured in order to maximize conversion, as the email. You should have an idea in advance of (i) how to introduce yourself (ii) which questions to ask and (iii) how to ask for the referral indirectly. In case you manage to get an in-person meeting instead of a call, that’s great but not strictly necessary.
You can find more on referrals at the second post at the following link: