I'd like to improve my English for working purpose.

I have to improve my English for working purpose. That's why I'd like to find out some people who wants to dialog with me about various topics.

I'd like to improve my English for working purposes. 

I have to improve my English for working purposes. That's why I'd like to find people who want( or, who would like) to talk with me about various topics.

dialogue*

Hi Roberto! :)

Only a few, easily fixable mistakes.The third sentence can depend on how you want to come across, "who would like" is generally more polite.