Set posts_per_page inside loop?

<?php
$pageNumber = (get_query_var('paged')) ? get_query_var('paged') : 1;
$maxposts = 3;

global $args;
$args = array(
    'posts_per_page' => $maxposts,
    'post_type' => 'news-item',
    'paged' => $paged
);
$temp = $wp_query;
$wp_query= null;
$wp_query = new WP_Query($args);

$style_classes = array('first','second');
$style_index = 0;
?>

<?php if (have_posts()) : ?>
    <?php $post = $posts[0]; $c=0; ?>
    <?php while ($wp_query->have_posts()) : $wp_query->the_post();?>

        <?php $c++;
            if( !$paged && $c == 1) : ?>

                <div class="most-recent-post">
                // Large post
                </div>

            <?php else :
                if($paged) :
                    //$args -> set( 'posts_per_page', 4 );
                    set_query_var( 'posts_per_page', 4 );
                endif; ?>

                <div class="post-block <?php $k = $style_index%2; echo "$style_classes[$k]"; $style_index++; ?>">
                // Normal posts
                </div>

        <?php endif;?>

    <?php endwhile; ?>
<?php endif; ?>


<!-- page navigation -->
<div class="page-navi">
    <?php if(function_exists('wp_paginate')) { wp_paginate(); } ?>
</div>
<?php $wp_query = null; $wp_query = $temp;?>