If you have a mix of text and numbers textscan as suggested by Geoff is a good solution.
If you only have text strsplit does exactly what you want and I feel that is a bit simpler to use.
strsplit('ab cd ef')
1×3 cell array
'ab' 'cd' 'ef'
You can specify the delimiter if it is not spaces that are your delimiters.
If you however want to split a string into single characters you could use cellstr
s = 'ab cd ef';
1×8 cell array
'a' 'b' '' 'c' 'd' '' 'e' 'f'