Fair percentages for songwriter

by Chantal
(Vancouver bc)

Hi I'm a singer songwriter..... I write songs all the lyric and the full melody.... I do not play an instrument well though.... I've just recently started writing with a piano player, I sing my song to him and he works out the chords.... Now when it comes to a percentage split, I see that a lot of the time it gets split 50-50..... Am I just being greedy wanting more then 50%, it's just that I feel I've written the whole song, lyric, melody, structure and hooks it doesn't seem fair to only give myself 50%.... I fully understand the music played underneath gives a song life but is there another way of splitting it that makes it more fair to me or should I just pay someone out full like an arranger to write out my chord structure..... I'm confused, i just know at the end of the day, it really feels like I should be getting more of a writers share..... Please any advice would be sooooo greatly appreciated I feel out of my element working with numbers and percentages.....