JustRunLah on "Custom post query but get only posts with IF statement"

Hello,
I will try to explain my issue here as much as I can, please let me know if it makes sense. I have searched for an answer to this but couldn't get it.

So, I have a custom post type called "race". Every race has custom fields, let's call them "A", "B", "C".

"A" can be an image field, and "B" a checkbox list.

What I want to do is to query and get / list only "races" that have a value on "A". So if "A" is an image, I can show a list of "races that have image". And if "B" can take values "HM", "FM", "5km", I can show only "races which are HM".

I have managed to do that by <?php if( get_field('A'): ?> and if( in_array( 'FM', get_field('race_category') ) or 'FM' == get_field('race_category') ): ?> respectively, the display works BUT, the query still gets all "race" posts, even if it only displays the ones which satisfy the criterion. I know this because of pagination.

For example, I have a total of 16 "race" entries, but only one with "FM" category. As you see at the link, I manage to get it, but it is displayed on the 4th page (current pagination is 5 posts / page, and this is alphabetically the last entry, so pagination works). http://www.justrunlah.com/blog/sg-races-db-full-marathon-events/

Also, I know how to use args arrays for simple stuff, for example I use the following to get entries that are within 2014 only, but I don't know how to implement the more complicated statements needed into the args code.

<?php
		global $paged;
		$curpage = $paged ? $paged : 1;
		$today = date('Ymd');
		$args = array(
		    'post_type' => 'race',
		    'orderby'	=> 'race_date',
		    'meta_key' 	=> 'race_date',
		    'order'	=> 'DES',
		    'posts_per_page' => 50,
		    'paged' => $paged,
		    'meta_query' => array(
		    'relation' => 'AND',
				array(
				'key'		=> 'race_date',
				'compare'	=> '<=',
				'value'		=> 20141231,
			    ),
				array(
				'key'		=> 'race_date',
				'compare'	=> '>=',
				'value'		=> 20140101,
			    )
				),
				);

		?>

In the following PasteBin I am giving you the code that gives that issue: http://pastebin.com/8hwdw0us

Thanks in advance