I don't understand why you have a 16 in your main attack stat. A dragonborn cleric can have a primary of 18 with STR. But I believe you are being a devoted cleric because of your wisdom being your attack stat?
You can try to have both if you are dragonborn. Or, you can be a longtooth shifter and get +2 str and wisdom. that way you can have a 16/16 in str/wis and be able to do both.
Truth be told dragonborn paladins can do both as well. As a cleric dragonborn you can pull it off with a 16 16 13 10 11 8. Con would be 13, your STR would be 18, your wis would be 16. CHA can either be 13 or 12.
Or you can do the same thing and make it wis/cha/con and str as 4th.
With that setup, your healing gets pretty sick. healing word=healing surge+wis mod+1d6.
Then, on top of that, many of your encounter powers, do in fact say, add CHA mod to healing done. So, that would be +3+4+heal surge
Sorry to go on such a tangent...but yea, +3 is ok. If your not sure, just be able to do both =)