I never found a way to search for a couple of words that are near each others (like on start and end of a line eg)

Does that work for you? I thought that's what a fuzzy finder is

I tend to use fzf for jumping rather than searching. To jump to a single instance you'd just type in some letters from each word and hit enter.

If I wanted all occurrences of lines that match a pattern I'd use vim-grepper (which uses Ag or ripgrep under the hood) and search with a regex.

If you're using Telescope you can use your fuzzy search to find the lines you want then use <C-q> to send them to your quickfix list.