Hello.

I think you want to say 

I want someone who can speak in Japanese together.

So ,

私は(I)　日本語で(in Japanese)　一緒に(together)　話せる人が(someone who can speak)　欲しいです(want)。

私は日本語で一緒に話せる人が欲しいです。(わたしはにほんごでいっしょにはなせるひとがほしいです)

is better.

I'm Japanese native speaker.So I can teach and talk with you.And I want some one who can speak in English with me.

I want to be your friend!!

だれかが日本語ではなしたいですか？

You wanted to write ほしい but this is combined with nouns not verbs. See here the difference between ほしい and -たい: <a href="https://www.learn-japanese-adventure.com/japanese-expression-desire.html" style="background-color: rgb(255, 255, 255);">https://www.learn-japanese-adventure.com/japanese-expression-desire.html</a>;