All you have to do is add a click handler on the request button, find the text of the 'h3', and set the modal form's "name" field value to that.
Take this JavaScript for example
jQuery(document).ready(function($){
// When the Request button is clicked
$('.request-form-btn').on('click', function(){
// Set 'title' to the closest product's h3 text
var title = $(this).closest('.prod-i').find('h3').text();
// Set the value of the "name" field to the title we got above.
$('[name="modal_name"]').val( title );
});
});
It appears you're using a premium theme, so add this to the "Custom/Body/Footer" scripts section of the website if there is one, otherwise you'll need to use one of the many "Header/Footer" script plugins that are available.
You can test this by pasting the JavaScript into the dev tools console on that page.