There are a ton of different ways to split up a string in Zsh. This gist attempts to show them with examples to help you build your own. I write Zsh scripts all the time, and still reference back to this gist, so there you go.
From the Zsh docs on Parameter Expansion Flags (yeah - I know... how would anyone ever find that if they didn't know where to look!?)
j:string: Join the words of arrays together using string as a separator.
s:string: Force field splitting at the separator string.
You can also read more by running man zshexpn. (Again, I know, right!? How would anyone know to look there!?)