broken chord is another way to say arpeggio....
for example, if you have reason to play a C-E-G-B chord(which is a C major 7), then instead of hitting all of the chords, play them one at a time, descending or ascending, which ever sounds best.
And really, take the advice of the previous poster, listen to what keyboard players are doing. It sounds too mechanical in print....
Do you have the 2004 WOW gospel dvd? I think it's the 2nd or 3rd tune on there, "It's In My Heart"...look at the beginning-that piano player is getting fancy, but look at the keyboard player, he's holding down one note, a high string sound. And it sounds great.
You can say, he isn't doing anything, why is he up there...but...he's up there and we aren't, so think about it....
When playing string sounds in this way, there are a couple of things to keep in mind, and you'll see guys doing this on those dvds-use the volume button to fade the sound in and out, especially at the end.
Try to connect the chords with common tones. In other words, when you have a string sound don't play like a piano player, play like a string player, or a conductor. Playing string sounds on a keyboard is kind of like play background organ pads, so that'll help ya there.