Form validation with submitbutton outside

I have problems with a form and a submitbutton outside the form tag.
I submit the form via js

$('#myformbutton').on('click', function(event) {

The form gets submitted when validation ok. But I do not get the inline validation with its messeages on a failure with the specific fields messeages. I just get the response ”FORM.VALIDATION_FAIL". So how to process the form validation from outside the form tag?