running preg_split("[\s]+/u", "I search 1, regex (regular expression) to: That's it is! Und über den Wolken müssen wir...", -1, PREG_SPLIT_NO_EMPTY)

array (
  0 => 'I',
  1 => 'search',
  2 => '1,',
  3 => 'regex',
  4 => '(regular',
  5 => 'expression)',
  6 => 'to:',
  7 => 'That\'s',
  8 => 'it',
  9 => 'is!',
  10 => 'Und',
  11 => 'über',
  12 => 'den',
  13 => 'Wolken',
  14 => 'müssen',
  15 => 'wir...',
)