The "ask" in your English example is used figuratively (metonymically) for "want, wish for, desire". Neither petere nor interrogāre have this meaning:
- petere means "to act in order to attain; to go for, strive for, seek, to ask for as a service etc.", and is therefore used not with questions but with things. The Spanish verb has had a few shifts of meaning since then, although it's still rather close.
- interrogāre means "to ask back and forth, to question, cross-examine etc.", but also "to put as a question, especially a yes-no one; to ask for information". In the latter sense it's synonymous with percontārī (percūnctārī), which gave Sp. preguntar.
The best option to express your meaning is optāre:
- quid amplius optēs? numquid est quod optēs ultrā?
You can also use dēsīderāre (in the form dēsīderēs), which is about abstract wishes as opposed to concrete desires. I don't think however that velle (velīs) "to want" will work: you want to express the generic second person ("one"), but it sounds like a polite direct question ("you who I'm talking to") due to the frequency of such use.
It's possible to use petere (petās), but only when implying an action directed at attaining the desired object. Similar to this quaerere (quaerās) "to search for". Another option is requīrere (requīrās) "to look for, want for", especially when meaning "to lack, need", but I think it would be used primarily to express irritation ("what more can you possibly want (from somebody)?").
Note that it's not possible to use the infinitive as you did in the generic meaning "anyone can" - you can use either the second person subjunctive, or include the verb posse in the 2p. subj. form possīs (as a rhetorical question) or simply as potest with the other verb passive, expressing generic possibility:
- quid amplius optāre possīs? nihil ultrā est quod optārī potest