local $_ = q(one, two, "three, four", five, six);
my @words = m(
  \s*        # gobble any leading whitespace
  (          # capture either:
    "[^"]+"  #   a group of quoted letters
  |          # or
    [^,]+    #   a group of non-quoted letters, except commas
  )
  (?:,|$)    # anchor the match to a comma, or end of string
)gx;