Just for anyone else trying to do this, this is how to do it. Use the preg_split function, with an or statement within it's parameter:
$array = preg_split('( users:| status:| count:)','users:Jack John Bob status:bad count:15',-1,PREG_SPLIT_DELIM_CAPTURE);
that will split the string into chunks with those supplied separators, so you can format the individual strings within the array.