Include Google api client in wordpress plugin

Solution:

First check the naming conventions

if is the folder Google or google and is the file Client.php or client.php

if everything is correct, Try this:

$file = glob(plugin_dir_path(__FILE__).”Google/Client.php”;
include_once $file;
and if you are using a template, use:

get_template_part()
WordPress now offers a function, get_template_part(), that is part of the native API and is used specifically for reusing sections – or templates – of code (except for the header, footer, and sidebar) through your theme.