Oh, the problem of enjoyment in a language lacking verbs to enjoy, to like and to need...
The equivalent depends on a context. If you want to be sarcastic, you just say Удачи! in an appropriate tone.
If you want to wish something pleasant, you just use a structure like 'have a nice / enjoyable + smth!''. In other words, you have to specify what is 'it' you wish an addressee to enjoy. The structure is not so simple to a native English speaker, e. g.:
Приятных уроков!
nice-GEN.PL.MASC. lesson-GEN.PL.MASC.
Приятной зарплаты!
good-GEN.SG.FEM. salary-GEN.SG.MASC.
Приятного воскресенья!
enjoyable-GEN.SG.NEUT. Sunday-GEN.SG.NEUT.
With words referring to it as a time unit or as an event, the adjective приятный is interchangable with счастливый.
Счастливого воскресения!
enjoyable-GEN.SG.NEUT. resurrection-GEN.SG.NEUT.