If you’re already using the Advanced Custom Fields for clients and you want to incorporate SEO fields for clients, I add this code to the <head> section (this is conditional):
<!-- For Titles -->
<?php if(get_field('seo_title')): ?>
<title><?php the_field ('seo_title');?></title>
<?php else: ?>
<title><?php if(is_front_page()): ?><?php bloginfo('name'); ?><?php else: ?>
<?php wp_title(''); ?><?php endif; ?></title>
<?php endif; ?>
<!-- For Descriptions -->
<?php if(get_field('seo_description')): ?>
<meta name="description" content="<?php the_field('seo_description');?>" />
<?php endif; ?>