Also, if there are three melee fighters and you are primarily depended on for healing, taking the Pacifist Healer feat is a favourite option of mine (though I've met a lot of people who don't like it).
Basically it means that if you hit a bloodied enemy, you are stunned, so you really end up avoiding combat, BUT, your healing abilities are maximized. Any power you have (Healer's Word included) that allows anyone to spend a healing surge heals an additional 1d6 + your charisma modifier at first level, 2d6 at 11th and 3d6 at 21st. If you select encounter powers that allow allies to spend surges (perhaps do some retraining, or if your DM allows you, just change a bunch) this basically gives you access to a large number of healing powers.Also, the character builder doesn't seem to list Healer's Mercy, and I'm about to post in the forum asking if it's still part of the rules or if there's a way to set it up in the builder, but, assuming it is still allowed,
Healer's Mercy: it is a Channel Divinity power that allows all allies in a close burst five to spend a healing surge. Combined with Pacifist Healer, it means you can heal the entire party. I am currently working on a Pacifist Cleric, thus why I have so much to say in response to this post haha.
EDIT: I'm an idiot, and just found Healer's Mercy in the Character Builder. I need to stop being stupid :P
But yeah, this basically makes for a super-effective healer, even from first level. I am currently makin this character 1st level, and he already has 3 healing encounter powers, one of which can be used twice and should be able to fully heal an ally, assuming the rolls aren't awful (my Healer's Word will heal 2d6+6+surge value HP) and one that provides healing to the entire party.
Only drawback being that you will only be killing enemies in an emergency, because you won't want to be hitting bloodied enemies and becoming stunned. Though there may be a way to avoid this? I'm not sure, just started working on this build.
ALSO, seeing as you're playing 16th level, you probably know WAY more than I do, so hopefully this was helpful and I don't sound like an idiot - feel free to correct me anywhere I may be wrong! Again this is something I'm just trying out, so it may not be fool proof.