$re = '/.*(?: DE: (.*))(?: ID: (.*)){0,1}(?: MOTIF: (.*))(?: REF: (.*)){0,1}/m';
$str = 'PRELEVEMENT EUROPEEN 2001427553 DE: MUTUELLE DE L\'INDUSTRIE DU PETROLE ID: FR69MIP108863 MOTIF: Prelevement 42CXK 024 de MIP du 01/
VIR RECU 0485970259S DE: CPAM VAR MOTIF: 180930001235180930001235 REF: 18093000123';
$subst = "Tiers:\t$1 \rid:\t$2 \rmotif:\t$3\r\r";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php