Victoria,
Sorry to be the bearer of bad news, but on the info you've so far provided, you've little or no chance of a fiance visa.
Essentially, your partner is unemployed and has no savings.
Additionally, it seems, he does not have his own accomodation,(is in rental accomodation), and relies on his sister to pay the rent.
1. He has to find "recognised" employment, where he receives a pay slip, and NI contributions are deducted.
2. He needs to build up some savings .... ideally in the region of £1500-£2000.
3. (after the first 2) he needs a letter from the landlord agreeing that an additional person can live in the accomodation.
I fear you've a long way to go
